System and method for acoustic container volume calibration

ABSTRACT

A system and method is disclosed for calibrating the volume of storage containers using ultrasonic inspection techniques. The exemplary ultrasonic calibration system comprises a plurality of acoustic devices controllably deployed in respective positions on the outside surface of the container. The acoustic devices include a transducer for sending acoustic signals across the internal volume of the container and sensors configured to detect the acoustic signals. The acoustic devices are in communication with a diagnostic computing device that controls the positioning and the operation of the acoustic devices and is further configured to determine the time time-of-flight of acoustic signals that travel between the various acoustic devices. Moreover, according to the specific arrangement of acoustic devices and the measured acoustic signal information, the control computer is configured to calculate the dimensions of the container and its internal volume.

FIELD OF THE INVENTION

The present invention relates to systems and methods for non-destructivetesting of structures, in particular to systems and methods for acousticmeasurement of the geometry of containers in a non-destructive manner.

BACKGROUND

In the oil and gas industry the storage tanks for crude and refinedproducts play a key part in the supply chain of hydrocarbons. Knowingthe exact volume of these storage units plays a critical role whentransferring products to and/or from the tanks. As a result ofvariations in external and internal conditions (i.e. temperature) andaging and also as a result of the weight of the liquid product (i.e.hydrostatic pressure), the tank volume can vary by as much as +/−0.2%.Considering a 250,000 barrel storage tank, this variation would resultin a volume of +/−500 barrels in volume change.

As a result of the high value of petroleum hydrocarbons, there is amandatory requirement for calibration of storage tanks. Tanks used forcustody transfer must be calibrated such that the transferred volume isvery accurately known (e.g., Less than 0.1% error). The most commonlyused techniques to perform this are; manual strapping (API MPMS 2.2A),optical techniques (Optical Reference Line Method ORLM—API Chapter 2.2B,Optical Triangulation Method (OTM)—API Chapter 2.2C, Electro-OpticalDistance Ranging Method (EODR)—API Chapter 2.2D) and liquid calibrations(API Standard 2555). However, these measurements have been found toproduce errors and are considered non-effective. In some cases, theforegoing testing techniques require tank downtime (e.g., emptying ofthe tank or otherwise halting the tank operation temporarily), whichaccumulates additional costs to the losses incurred. Moreover, many ofthe foregoing testing techniques are invasive in that they requireaccessing the internal volume of the tank and also can be destructive.

In the oil and gas industry, ultrasonic probes have been used todetermine the health and structural integrity of pipelines and vesselsat localized points. Known systems for measuring wall thickness usingultrasound are based on the concept of using the time-of-flight (TOF)for sound to travel between the outer and inner surfaces of the wall todetermine distance traveled. In such implementations, the TOF analysisof the ultrasonic signals return journey through the metallic medium(i.e. pipe or vessel) is used to determine the thickness of the walland, thus, degradation as a result of corrosion. Similarly, there hasbeen work on sending acoustic waves along the length of pipes todetermine if there are cracks or other anomalies that would causeunexpected reflections. However, such systems are reliant on known orassumed pipe dimensions and are not configured to determine thegeometric profile of the pipe. Rather, the geometric measurement of thecontainer is assumed or determined using the known alternative methodsmentioned above.

In the case of tank inspection, the aforementioned methods require highlevels of calibration and also require a couple of days' worth of work(e.g., including the erection and use of high scaffolding to deploy themeasuring systems and conduct the measurements). Therefore,calibration/measurement of the tanks is done infrequently, leading toerroneous tank volumes and lost sales revenue.

The existing methods for tank calibration present significant drawbacks.For instance, using the current standards, it can take 1-2 days of workto perform the calibration. As a result, calibration of storage tanks isperformed infrequently thus leading to inaccurate measurements of theactual volume stored within the tank or transferred to and from thetank, which can be costly. For example, a traditional timeframe betweencalibrations can be between five and fifteen years.

What is needed are systems and methods for calibrating the volume ofstorage tanks that addresses the limitations associated with theefficiency of performing calibration using existing systems. Morespecifically, what is needed are systems and methods for accuratelyperforming tank calibration that can be deployed and operated in arelatively quick, low-cost, and non-invasive manner. What is also neededis a system that can be deployed quickly and on-demand and thusfacilitates detection of changes in tank volume on a more frequent basis(e.g., on a daily basis or even per-fill basis).

It is with respect to these and other considerations that the disclosuremade herein is presented.

SUMMARY

According to an aspect of the present invention, there is provided amethod for measuring a container containing a medium therein using aplurality of acoustic devices. The method includes the step of deployingthe plurality of acoustic devices into respective positions on anexterior surface of a circumferential wall of the container. Inparticular, the acoustic devices include an ultrasonic transducer and anultrasonic sensor. The transducer is acoustically coupled to the surfaceand is configured to transmit one or more ultrasonic signals through thewall of the container and across the interior volume of the container.In addition, the sensor is acoustically coupled to the surface andconfigured to detect the one or more ultrasonic signals. The method alsoincludes the steps of transmitting one or more ultrasonic signals usingthe transducer at a respective impulse time and detecting the one ormore signals, using the sensor, and recording a respective detectiontime. The method also includes the step of calculating, by a computingdevice that is in electronic communication with the transducer and thesensor, respective times of flight (TOFs) for the one or more signalsbased on the respective impulse times and respective detection times.More specifically, each respective TOF is an elapsed time for a signalto travel through the interior volume between the transducer and thesensor along a respective flightpath. The method also includes a step ofaligning one or more of the acoustic devices based on the calculatedTOFs. In particular, the devices are aligned in one or more of acircumferential direction and a longitudinal direction relative to thecircumferential wall of the container. According to the method, thesteps of transmitting, detecting and calculating are repeated. Inaddition, the method includes the step of calculating, with thecomputing device, a distance between the aligned transducer and sensorbased on the re-calculated TOF and a speed of sound through the medium.Lastly, the method includes the step of determining, with the computingdevice, the volume of the storage container based on the calculateddistances.

According to a further aspect of the present invention, there isprovided a system for measuring a volume of a storage container. Thesystem comprises a plurality of acoustic devices that are configured tobe acoustically coupled to an exterior surface of a circumferential wallof the container at respective positions, the acoustic devicesincluding. In particular, the acoustic devices include an ultrasonictransducer configured to transmit one or more ultrasonic signals acrossan interior volume of the container that is bounded by the wall, and anultrasonic sensor configured to detect the one or more ultrasonicsignals. The system also includes a robot configured to controllablydeploy one or more of the acoustic devices on the surface. Inparticular, the robot includes a drive system and one or more positionsensors for monitoring a position of the robot.

The system also includes a computing system that comprises anon-transitory computer readable storage medium and one or moreprocessors in electronic communication with the plurality of acousticdevices and the computer readable storage medium. The computing systemalso includes one or more software modules comprising executableinstructions that are stored in the storage medium and are executable bythe processor. In particular, the software modules include an acousticcontrol module that configures the processor, using the transducer, totransmit one or more acoustic signals at respective impulse times. Inaddition, the acoustic control module further configures the processor,using the sensor, to detect the arrival of the one or more signals andrecord respective detection times. The software modules also includes anacoustic analysis module that configures the processor to calculate arespective time of flight (TOF) for the one or more acoustic signalstraveling between the respective positions of the transducer and thesensor. Further the configured processor calculates a respectivedistance therebetween based on the respective TOF. The software modulesalso includes a position control module that configures the processorto, using the robot, adjust the respective position of one or more ofthe transducer and the sensor on the surface. In addition, for eachadjusted respective position, the processor is configured tore-calculate a respective distance between the transducer and the sensorbased on one or more acoustic signals traveling therebetween. Thesoftware modules also include a geometric analysis module thatconfigures the processor to calculate a volume of the storage containerbased on the calculated respective distances and correspondingrespective positions of the transducer and the sensor.

These and other aspects, features, and advantages can be appreciatedfrom the accompanying description of certain embodiments of theinvention and the accompanying drawing figures and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a high-level diagram illustrating an exemplary configurationof a system for ultrasonic calibration of the volume of storagecontainers according to an embodiment of the invention;

FIG. 2 is a block diagram illustrating an exemplary configuration of acontrol computer according to an embodiment of the present invention;

FIG. 3 is a flow diagram showing a routine that illustrates the systemsand methods for ultrasonic calibration of the volume of storagecontainers according to an embodiment of the present invention;

FIG. 4A is a simplified side view and top view of an exemplary containervolume calibration system according to an embodiment of the presentinvention;

FIG. 4B, is a conceptual side-view of the exemplary container volumecalibration system of FIG. 4A;

FIG. 4C is a simplified side view of the exemplary container volumecalibration system of FIG. 4A;

FIG. 5 is a simplified side view of an exemplary container volumecalibration system according to an embodiment of the present invention;

FIG. 6 is a simplified side view of an exemplary container volumecalibration system according to an embodiment of the present invention;

FIG. 7 is a simplified side view of an exemplary container volumecalibration system according to an embodiment of the present invention;

FIG. 8 is a simplified top view of an exemplary container volumecalibration system according to an embodiment of the present invention;and

FIG. 9 is a simplified top view of an exemplary container volumecalibration system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION

By way of overview and introduction, a system and method is disclosedfor calibrating the volume of storage containers. More specifically, thesystems and methods disclosed herein are directed to measuring anddetermining the dimensions of large petroleum storage tanks so as tocalculate the volume of such tanks using ultrasonic inspectiontechniques. Preferably, the systems are configured to perform thecalibration from the exterior of the container on-demand during the useof the containers in the field. “Calibrating,” i.e., knowing the exactvolume of the storage containers, plays a critical role whentransferring products to and/or from the tanks. Routine calibration isnecessary due to variations in external and internal conditions (i.e.temperature), aging of the tank, and also as a result of the weight ofthe liquid product (i.e. hydrostatic pressure). For example, acontainer's volume can vary by as much as +/−0.2%, considering a 250,000barrel storage this would result in a volume of +/−500 barrels in volumechange.

Ultrasonic testing is a non-destructive and non-invasive testingtechnique based on analyzing the propagation of ultrasonic waves in thematerial being tested (e.g., the wall of the container). In theembodiments described herein, the ultrasonic measuring techniques areperformed to measure the volume of large storage containers that aretypically generally cylindrical in shape and are typically made of steelor other metals and alloys. However, the disclosed techniques andsystems can also be applied to calibrate the volume of structures madeof other materials such as concrete, composites, natural materials(e.g., wood) or combinations of the foregoing. In addition, the systemsand techniques disclosed herein can also be applied to measure thevolume of containers having different sizes and shapes as well. Forinstance, the exemplary embodiments can be used to measure the volume ofopen or closed vessels, tanks and other such containers or conduits ofvarious sizes.

In some exemplary configurations, the ultrasonic container volumecalibration system comprises a plurality of acoustic devices havingassociated electronic hardware and/or software suitable for controllingtheir operation. The acoustic devices are configured to be attached tothe exterior surface(s) of a storage container, for instance, by hand orusing a mobile robotic platform and the like, thereby defining one ormore arrays of devices. The acoustic devices are configured to takeacoustic-based measurements that enable the determination of thecontainer's volume by a diagnostic computing device that is incommunication with the acoustic devices. More specifically, the acousticdevices include one or more acoustic sensors configured to receive,measure and process acoustic signals transmitted across the internalvolume of the container. The acoustic devices also include at least oneacoustic signal generating element (hereinafter also referred to as a“transducer”) that is configured to transmit the acoustic signalsthrough the wall of the container and across the interior volume of thecontainer and, accordingly, through any particular medium containedtherein (e.g., oil, water, air and the like).

In some basic configurations, the ultrasonic container volumecalibration system includes one transducer and one sensor. Thetransducers and sensors can be individual acoustic devices, however, insome implementations a transducer and sensor can be integrated into asingle transceiver unit configured to transmit and receive acousticsignals. In more complex configurations the system includes a pluralityof acoustic devices placed on the container surface at differentlatitudes on the surface (e.g., different heights on the container wall,as measured in the longitudinal direction relative to the base) and/orplaced at different circumferential positions (i.e., spaced apart aboutthe circumference of the container).

The acoustic sensors and transducers are connected to and controlledusing a diagnostic computing device (hereinafter referred to as thecontroller or control computer), which is configured to determine thetime between the transmission of an acoustic signal using the transducerand the arrival of the acoustic signal, which traveled across theinterior volume of the container, at a respective sensor. The traveltime of an acoustic signal between devices is referred to as the“time-of-flight” or “TOF.” In addition, similar TOF information foradditional acoustic signals that arrive at one or more of the sensor(s)can be measured/collected as well (e.g., reflections of the firstacoustic signal off the interior wall of the container, or a secondacoustic signal transmitted by one or more of the transducers).

According to a salient aspect, in some implementations, the acousticdevices can be controllably positioned on the surface of the containerand aligned in one or more directions. For instance, a sensor and atransducer can be longitudinally aligned such that they are at the sameheight on the container wall, as measured relative to the base of thecontainer, which is assumed to be on level ground for simplicity. Inaddition or alternatively, two devices can be aligned on the outersurface of the container in other directions, for instance,circumferentially, such that the devices are located on directlyopposite sides of the container and the acoustic signals travellingtherebetween follow a path that extends across the interior diameter ofthe container. In addition or alternatively, in some implementations, atransceiver operating in transmit and receive mode can be positioned andaligned on the container surface such that it transmits acoustic signalsthat travel across the interior volume, reflect off the interior surfaceof the opposite side of the wall and travel back along the same path tothe point of origin, where it can be received using the transducer.

Accordingly, based on the time between the transmission and detection ofacoustic signals and the relative position of the acoustic devices,various dimensions of the container can be calculated by the controlcomputer, including, for example and without limitation, diameter,circumference, volume, and height. The dimensions of the container arealso calculated based on the speed of sound through the medium that iscontained within the interior volume and that the acoustic signalstravel through. Accordingly, an accurate understanding of the speed ofsound in the particular medium that is contained within the container(e.g., oil, refined product, water, air and the like) can be importantto determining the actual length of the acoustic signal's flightpath andthe corresponding dimensions of the container. In addition totime-of-flight analysis, transient analysis can be performed byextracting information on the phase difference between the acousticsignals to determine changes in the time of flight.

According to another salient aspect, the disclosed system for acousticcalibration of can be configured to controllably move one or more of theacoustic sensing devices into position before and/or during thecontainer volume calibration process, for instance using roboticcarriers that deploy the one or more acoustic devices on the exterior ofthe container being calibrated. In such embodiments, the roboticcarriers can include memory and one or more processors that areprogrammed to position the devices and perform acoustic distancemeasurements autonomously and/or controlled remotely using the controlcomputer. In particular, the robots can controllably move the acousticdevices so as to measure the diameter of the container at differentpoints along the height of the container and/or around the circumferenceof the container. For instance, one or more robotic platforms can beconfigured to follow a pre-determined and pre-programmed path along thesurface, say, a helical path about the container's circumferencestarting near a top edge of the wall to the base, so as to take acousticmeasurements at different heights and circumferential positions andstore the temporal information from the acoustic signals and positionalinformation of the acoustic devices for each measurement in storage atthe robotic platform or control computer.

In addition, in such embodiments, alignment in a variety of differentdirections/dimensions can be achieved among the acoustic devices andrelative to the surface of the container wall to improve calculations ofvolume of a container. As a result of measuring distance across theinterior volume of the container from multiple positions on theside-wall of the container, a two-dimensional map or three dimensionalmodel of the container can be created using the measured distancestherebetween and principles of geometry.

An exemplary system for ultrasonic calibration of the volume of astorage container 100 is shown in FIG. 1. As shown in FIG. 1, theultrasonic container volume calibration system 100 includes one or moreacoustic devices that are arranged for measuring the volume of ametallic, cylindrical storage container 150. The container includes acircumferential side wall that bounds the interior volume 165 of thecontainer. It can be appreciated that cylindrical containers are notnecessarily exact cylinders that extend vertically. For example andwithout limitation, the cylinder's circumference can differ at differentheights on the wall, the side-wall of the container can have anon-uniform curvature and the container can have other such variationsin geometry. By way of further example, in some implementations, thecylinders can be oriented such that the central axis extendshorizontally relative to the ground. Moreover, the exemplary techniquesdisclosed herein are similarly applicable to calibrating the volume ofcontainers having other shapes, for instance, spherical tanks, however,it can be appreciated that such alternative container shapes can requirea different set of known parameters (e.g., relative placement ordistance between measurement devices) in order to calculate thecontainer volume.

The one or more acoustic devices are configured to be deployed onto theexterior surface 155 of the side wall (e.g. by hand, robot, etc.) andacoustically coupled to the wall of the container. Accordingly, theacoustic devices are configured to transmit acoustic signals and/orreceive acoustic signals traveling through the volume of the container.The one or more acoustic devices preferably include at least oneacoustic sensor and at least one acoustic transducer.

As shown in FIG. 1, the acoustic devices can include one or more sensors120A (shown on the opposite side of the container), 120B (shown on theopposite side of the container) and 120C that are arranged on thesurface 155. In addition, the system 100 includes one or moretransducers, for instance, transducer 130A, that is configured togenerate and apply acoustic signals to the surface 155 that are suitablefor detection by acoustic sensors. Additional transducers such astransducer 130B and 130C can also be used.

The term “longitudinal axis” 116 is intended to refer to the centralaxis of the container taken along the axis of elongation of thecontainer. As shown in FIG. 1, the longitudinal axis 116 is a centralaxis extending between the base of the container (e.g., where thecontainer is anchored or placed on the ground) and the opposing top endof the container. For simplicity, the exemplary systems and methods aredescribed under the assumption that the base of the cylindricalcontainer is anchored on flat ground and the circumferential wall of thecontainer extends away from the ground in the longitudinal direction(i.e., in the vertical direction relative to the ground/base of thecontainer). Accordingly, the directions that the longitudinal axis 116extends is also referred to as the “longitudinal direction” 116. As canbe appreciated, given a container assumed to be anchored to the groundat its base, and as you move away from the base, along the longitudinalaxis, there is an infinite set of transverse or “latitudinal” planesextending through the cross-section of the container, on which theacoustic devices can be placed against the exterior surface of thecontainer wall.

Two acoustic devices are described herein as being aligned in thelongitudinal direction (also referred to as being in longitudinalalignment) when they have respective positions on the surface of thecontainer that fall in the same transverse or latitudinal plane, whichis a plane that is perpendicular to the longitudinal axis 116 andbisects the container 150. In other words, devices that are aligned inthe longitudinal direction have the same height (i.e., latitude)relative to the base of the container along the longitudinal axis (e.g.,both devices are 9 feet off the ground as measured from the base in thelongitudinal direction).

Because the cylindrical container is a three-dimensional structurehaving a circumference, the term “circumferential direction” 118 isintended to refer to the direction along the surface 155 that extendsabout the circumference of the container and that is perpendicular tothe longitudinal axis 116, at a given latitude. In particular, thecircumferential direction about the container's circumference includesthe counter-clockwise direction 114 and the clockwise direction 112,when viewing the container from above, for example.

Devices are referred to herein as being aligned in the circumferentialdirection, in circumferential alignment or circumferentially aligned,when their respective positions on the surface 155 fall in the samelongitudinal plane (i.e. a plane extending through and along thelongitudinal axis) and, preferably, the devices are on opposite sides ofthe container. For instance, two devices located at +270 degrees and+90, respectively, relative to a 0 degree reference axis 102 (when thecylindrical container is viewed from the top-view) are circumferentiallyaligned irrespective of their respective latitudes on the surface.

Because the surface of a wall of the container can also be described asan “unwrapped” two-dimensional surface, in two dimensional space, thecircumferential direction 118 can be referred to as the “horizontaldirection” (i.e., perpendicular to the longitudinal direction assumingthat the base of the container is on level ground) or, more generally,the “transverse direction,” which refers to one or more directions alongthe surface 155 that are perpendicular to the longitudinal direction116, at respective latitudes.

Returning to FIG. 1, preferably, each transducer generates acousticsignals that travel from a respective point of origin through theinterior volume 165 of the container 150. The terminology traveling“through the container” is intended to mean that the acoustic signalpropagates through the thickness of the wall and across the interiorvolume 165 and, thus, through one or more mediums within the interiorvolume that lie in the signal's flightpath. In the exemplary system 100deployed on the cylindrical storage container 150, the acoustic signalspreferably travel through the cross-section of the container. However,it can be appreciated that, in some implementations, one or more of thetransducers can be configured to generate acoustic signals that radiatealong the surface 155 of the wall (e.g., propagate within the thicknessof the wall) in one or more of the directions that the wall extends, forinstance, in the circumferential direction 118, in the longitudinaldirection 116, and/or a combination of the foregoing. Exemplary systemsand methods for measuring container volume based on circumferentiallytraveling acoustic signals is more fully described in co-pending andcommonly assigned U.S. patent application Ser. No. entitled “ACOUSTICCALIBRATION ARRAY FOR TANKS AND VESSELS,” to inventors Parrott et al.,filed on [even date herewith], and bearing Ser. No. [to be assigned, andSer. No. 15/491,588, which is hereby incorporated by reference as iffully set forth herein in its entirety.

As previously noted, in some configurations, the one or more transducersand one or more sensors are individual devices configured to operate ina “pitch-catch” mode, in which the transducers transmit the acousticsignals and they are received by the sensor. In addition oralternatively, at least a transducer and a sensor can be integrated intoa single “transceiver” unit configured to both transmit and receiveacoustic signals. In such an implementation, the transceiver can beconfigured to operate in “pulse-echo” mode, in which a transducercomponent transmits the pulse through the wall of the container and theinterior volume towards an opposing sidewall of the container, and asensor component receives the echo of the signal that is reflected offof the opposing wall of the container back toward the transceiver.

As shown in FIG. 1, the acoustic devices are electrically connected to(connection means not shown) a control computer 110 that is configuredto coordinate the operation of the ultrasonic container volumecalibration system 100 and the various acoustic devices. The controlcomputer 110 is a computing device and/or data processing apparatuscapable of communicating with the various devices of system 100,receiving, transmitting and storing electronic information andprocessing such information so as to measure and calibrate the volume ofstorage containers, as further described herein. As further described inrelation to FIG. 2, the control computer comprises a processor (notshown), which executes one or more software modules in the form ofmachine implementable code and, in doing so, is configured to controlthe transmission and reception of ultrasonic signals by the transducerand sensors, respectively. In addition, the software configures thecontrol computer to analyze the acoustic signal information, asgenerated by a transducer and measured by a sensor, and calculatevarious dimensions of the container (i.e., the container's geometry). Insome implementations, the software can also configure the processor toevaluate structural conditions of the container as well as otheroperational characteristics of the container (e.g., the volume of thecontents within the container, classify the contents, or structuralintegrity of the container walls, and the like).

More specifically, the control computer 110 is configured to determinethe time between the generation of one or more acoustic signals by oneor more transducers, such as transducer 130A, and the arrival of the oneor more acoustic signals traveling through the wall and across theinternal volume of the container at one or more of the sensors, such as,sensor 120A. Accordingly, the control computer is further configured tocalculate the distance traveled by the signals and the dimensions of thecontainer based on the time between the sound impulse and reception ofthe impulse waves and further based on a known speed of sound throughthe material of the wall. In addition, similar “time-of-flight”information for additional acoustic signals that arrive at the sensor(s)can be measured/collected using the control computer 110 as well, forinstance, a time-of-flight for a reflection of a first acoustic signal,or the TOF of other acoustic signals generated by another transducer andthe like.

As the speed of sound through the volume of the container can varydepending on the material properties of one or more mediums that theacoustic signals pass through, an accurate understanding of thespeed-of-sound in the particular medium(s) contained within thecontainer (i.e. oil, refined product, water, a mixture of mediums, andthe like) is important to accurately determine the distance traveled bythe acoustic signals and the dimensions of the container. Morespecifically, different liquids within the container will have differentacoustic impedances, where this will relate to a different flight time.Also the presence of a different liquid may also be noted from theamplitude of the acoustic signal.

In some implementations, the speed of sound can be assumed based on theknown contents of the container as well as known material properties ofthe container wall. For instance, the speed-of-sound in a known mediumcan be determined by performing offline measurement in a calibrated tankof known dimensions. In addition or alternatively, in someimplementations, the system 100 can be configured to measure the speedof sound dynamically while the container is “online.” More specifically,two (2) or more acoustic devices having a known separation can be usedto calibrate the speed-of-sound measurement that informs the calibrationof the container volume. For instance, the speed-of-sound calibrationmeasurements can be carried out online by placing a base “strap” on thecontainer having a known diameter, measuring the TOF of an acousticsignal transmitted across the diameter of the container andback-calculating the speed-of-sound based on the known diameter andmeasured TOF.

In some exemplary implementations, a single transducer and sensor can beutilized to conduct the container calibration, as further describedherein. In some more complex implementations, one or more arrays ofacoustic devices can be deployed onto the container and utilized to moreaccurately calculate the container dimensions. An array can comprise oneor more acoustic sensors and, in addition or alternatively, one or moreacoustic transducers.

In some implementations, the acoustic devices defining an array can bespaced apart a known amount in one or more directions along the surface.For instance, a phased array of multiple transducers that are spacedapart in one or more of the longitudinal direction 116 can be used. Asfurther described herein, utilizing at least two acoustic devices thathave a known spacing can aid in the calibration of the system 100 andaccuracy assurance when using the system 100 to calibrate the volume ofthe container. Similarly, in some implementations, the acoustic sensorscan be individually arranged at known circumferential positions aroundthe container. As a result, the accuracy and speed of calculations canbe improved. Moreover, based on the controlled placement of at leastthree acoustic devices relative to one-another on the container wall,the acoustic signal information can be used by the control computer toaccurately triangulate and validate the respective positions of theacoustic devices. Thus, the dimensions of the container can be moreaccurately measured in multiple dimensions and used to create atwo-dimensional model by “unwrapping” the outer wall of the containerand, in addition or alternatively, a three-dimensional model of thecontainer volume.

Acoustic Sensors:

The acoustic sensors, e.g., sensors 120A-120C, can be any variety ofacoustic sensors or transceivers that are suitable for being mounted tothe external surface of the container, detecting and receiving acousticsignals from the wall of the container and processing such information,as would be understood by those in the art. Preferably, the acousticsensors have tips in contact with the surface 155 that are of a suitablesize to achieve the required accuracy in the measurement and, thus,minimize error in detection of the acoustic signal. Accordingly, thesize of the tip can be defined as a function of the necessary accuracyof the system.

In some exemplary configurations, piezoelectric transducers (contacttransducers) can be used. In addition, dual element transducers that cantransmit and receive acoustic signals (i.e. two piezoelectric crystalsin the one transducer housing) can be used as well. Preferably in thiscase, the resonant frequency of the acoustic transducer can be below 1MHz. Lower frequency transducers can be used (i.e., in the 100's of KHzrange) where the time of flights can be compared. The frequency of thetransducer can be selected based on the understanding that, as a resultof attenuation of the signal, the expected amplitude will decrease asthe frequency increases.

Preferably, the acoustic sensors are in electronic communication withthe control computer 110 such that the control computer can controloperation of the sensors and such that the sensors can provide acousticsignal data to the control computer for further processing. Morespecifically, in operation, the acoustic signals received by a sensorare converted to electrical signals that can be further processed,either by the sensor or the control computer, to extract signalmeasurement information including the temporal and intensity propertiesof the received acoustic signals.

Acoustic Signal Generators:

The basic principle of operation of an ultrasonic/acoustic signalgenerating device is that it converts an electrical signal to anacoustic signal, as would be understood by those in the art. As notedabove, an acoustic signal generating device, also referred to as atransducer (e.g., transducer 130A-130C), can be any variety of acoustictransducers or transceivers that are suitable for generating acousticsignals that travel through the wall of the container 150 and across theinternal volume 165 of the container and for being detected using theone or more sensors.

In the following description, the term “acoustic” is to be construedbroadly to include any acoustic signals, for example in a frequencyrange of 100 Hz to 50 MHz, more optionally in the ultrasonic acousticradiation range. Various types of acoustic signals can be used forinstance, impulses/pulses, a stream of pulses wherein the pulses occurat a particular frequency and each pulse has a particular waveform andresonant frequency (which is the frequency of the signal within thepulse), waves having a particular frequency, amplitude, wavelength andthe like. In an exemplary preferred implementation, the acoustictransducer can be configured to generate a train of acoustic pulses. Aswould be understood, controlled parameters of the individual pulses inthe train can include the period (1/frequency), resonant frequency andpulse duration. Parameters relating to the train can include a pulserepetition period and a duty factor. In such an implementation, the timebetween pulses is not critical factor, however, the time between pulsescan be calculated and controlled such that pulses do not overlap. Forinstance, in the exemplary application of measuring storage containers,and considering the time of flight, delays between pulses of between 50ms and 1000 ms second are suitable, although this is not a criticalparameter (e.g., when traveling over thirty (30) meters the sound pulseshould perform the return journey in close to 42 milliseconds). Thefrequency of the pulses can be determined by the resonant frequency ofthe transmitter. As mentioned above, a resonant frequency of theacoustic transducer below 1 MHz, and more optionally in the range of10's to 100's of KHz, can be suitable in view of the distance traveledin the exemplary storage container measurement applications describedherein.

A transducer can be configured to apply ultrasonic acoustic signals tothe wall of the container 150 such that the signal radiates away fromthe point of origin of the signal. Preferably, the transducer isconfigured to be positioned relative to the surface of the container(e.g., at an angle that is normal to the container wall) and direct theacoustic signal such that it travels in one or more defined directionsfrom the point of origin across the interior volume 165 of thecontainer. In some configurations, the acoustic signal is directed alonga specific path across the tank and perpendicular to the surface of thecontact area between the acoustic transducer on the surface of thecontainer wall. In some configurations, the transducer is configured tocontrollably transmit the acoustic signal across the interior volume ofthe container along a path that is perpendicular to the longitudinalaxis 116 and along the diameter of the container. In addition oralternatively, the transducer is configured to controllably transmit theacoustic signal across the interior volume of the container at a givenangle. For instance, directionality of the acoustic signal can becontrolled by controlling the angle of the transducer relative to thecontainer surface. More specifically, when operating in a pitch andcatch mode, the acoustic signal can be transmitted at a known angleprovided that the position of the catching transducer can be calculatedand positioned adequately. Angled transmission (e.g., not directlyacross the container diameter) would increase the acoustic pathtravelled by the signal and can allow for a more accurate measurement ofchanges in volume of the tank. Such a configuration can also require alower frequency signal (e.g., 10's to 100's of KHz) depending on thepath length and as a result of signal attenuation within the container.In addition, in applications where the surface of a container may notaccessible (e.g., an insulated container) the use of a waveguide may beused to direct the acoustic signal into the container.

Preferably, an acoustic transducer is in electronic communication withthe control computer 110 such that the control computer can controloperation of the transducer. In some implementations, the transducer canbe configured to introduce acoustic signals having certain properties,namely, specific frequencies or specific ranges of frequencies. Theproperties of the acoustic signals can be a function of the specifichardware configuration of the transducer and, in addition oralternatively, controlled using the control computer.

In the case of using more than one transducer, the transducers can beindividually controlled to facilitate differentiation between theirrespective signals. For instance, the transducers can be operated as aphased array, wherein the acoustic signals sent out by each transduceris controlled in time using the control computer 110, thereby allowingfor the differentiation between signals received by the one or moreacoustic sensors. In addition or alternatively, transducers that areconfigured to emit differing frequencies for emission and reception canbe utilized to facilitate the differentiation between signals based onsignal frequency using the control computer 110. Other suitable signalcharacteristics can also be selected or modulated in the methods andsystems herein, for instance, the amplitude and wavelength of theacoustic signals can be modulated or defined by the control computer.

Robotic Deployment:

In some implementations, one or more of the acoustic devices can beattached in a respective position on the exterior of the container so asto provide a long-term or permanent calibration system capable ofmeasuring a particular container's volume periodically in an on-demandfashion. In addition or alternatively, in some implementations, one ormore of the acoustic devices can be deployed on a temporary basis suchthat the devices can be used to calibrate the volume of differentcontainers. It can also be appreciated that a combination of fixed andtemporarily deployed acoustic devices can also be utilized.

Accordingly, in some configurations, the system can include one or morerobotic carriers or “robots” that are configured to autonomously andsemi-autonomously deploy one or more of the acoustic devices on thecontainer being calibrated, thus eliminating the need for scaffoldingwhen deploying the devices into position on the container wall. Forinstance, as shown in FIG. 1, the acoustic transducer 130C can becontrollably deployed using a robot 160. Deployment of an acousticdevice by a robot can include attaching the device to the container atrespective locations. Accordingly, in some configurations, a robot candeploy multiple different acoustic devices. In other configurations, anacoustic device can be mounted to a robot such that deployment comprisesmoving the robot into position and which places the acoustic device inacoustic communication with the surface 155 of the container wall andwhich can thereafter move to another position, as necessary. In such anarrangement, the robot can reposition itself and optionally move theacoustic device into engagement with the container under programmaticcontrol of code implemented by the system.

As would be understood by those in the art of robotics, each robot 160is a mobile robotic device that includes a body and a motion system formoving the robot during operation. The robot can be powered by, forexample, solar cells, batteries, or any other suitable power source. Therobot can include functional hardware components specifically designedto facilitate performing operational tasks, for instance, sensors fordetecting height, position, orientation of the robot, and the like. Therobot hardware can also include on-board acoustic sensors andtransducers used in the container volume calibration processes and, inaddition or alternatively, components suitable for transporting anddeploying acoustic devices configured to operate in a stand-alonefashion. The robot can include electronic circuitry within the body thatincludes a memory and/or computer readable storage medium which areconfigured to store information relating to the operation of the robotsuch as configuration settings and one or more control programs thatfacilitate the performance of the container volume calibrationoperations.

According to a salient aspect, in some embodiments, the system 100 canbe configured to controllably deploy the acoustic devices into positionbefore and/or during implementation of the container volume calibrationprocess so as to accurately measure the container volume in an automatedfashion. More specifically, a robot-based deployment solution can beimplemented to automatically execute more complex container volumecalibration procedures with a high degree of precision thereby improvingthe accuracy of the container calibration results by virtue capturingacoustic measurements for any number of different sensor and/ortransducer placement schemes. For example, robots can be controlled bythe control computer 110 to systematically move the sensor(s) and/or thetransducer(s) into different positions on the container wall (e.g.,various heights, circumferential positions, relative positions, absolutepositions etc.) such that acoustic measurements can be taken for eacharrangement of devices and the measurements can thereafter be analyzedindividually and in combination to generate a detailed map of thecontainer's shape and, more particularly, the container volume.

Control Computer:

The exemplary control computer 110 is further described in reference toFIG. 2. As shown, the control computer 110 can be arranged with varioushardware and software components that serve to enable operation of thesystem 100, including a circuit board 215, a processor 210, a memory220, a display 235, a user interface 225, a communication interface 250and a computer readable storage medium 290.

The processor 210 serves to execute software instructions that can bestored in the storage 290 and loaded into the memory 220. The processor210 can be a number of processors, a multi-processor core, or some othertype of processor, depending on the particular implementation. Thedisplay can be displayed on a touchscreen or other display operativelycoupled to an input device (not shown).

Preferably, the memory 220 and/or the storage 290 are accessible by theprocessor 210, thereby enabling the processor 210 to receive and executeinstructions stored on the memory 220 and/or on the storage 290. Thememory 220 can be, for example, a random access memory (RAM) or anyother suitable volatile or non-volatile computer readable storagemedium. In addition, the memory 220 can be fixed or removable. Thestorage 290 can take various forms, depending on the particularimplementation. For example, the storage 290 can contain one or morecomponents or devices such as a hard drive, a flash memory, a rewritableoptical disk, a rewritable magnetic tape, or some combination of theabove. The storage 290 also can be fixed or removable, local storage orremote storage such as cloud based data storage systems.

One or more software modules 230 are encoded in the storage 290 and/orin the memory 220. The software modules 230 can comprise one or moresoftware programs or applications having computer program code, ascript, or a set of interpretable instructions executed in the processor210. Such computer program code or instructions for carrying outoperations and implementing aspects of the systems and methods disclosedherein can be written in any combination of one or more programminglanguages or scripts. The program code can execute entirely on thecontrol computer 110, as a stand-alone software package, partly on thecontrol computer and partly on a remote computer/device (e.g., sensors,transducers and/or robots) or entirely on such remote computers/devices.In the latter scenario, the remote computer systems can be connected tocontrol computer 110 through any type of electronic data connection ornetwork, including a local area network (LAN) or a wide area network(WAN), or the connection can be made through an external computer (forexample, through the Internet using an Internet Service Provider).

Preferably, included among the software modules 230 is an acousticcontrol module 270, an acoustic analysis module 272, a geometricanalysis module 274, and a position control module 276 that are executedby processor 210. During execution of the software modules 230, theprocessor 210 is configured to perform various operations relating tothe calibration of storage containers, as will be described in greaterdetail below.

It can also be said that the program code of the software modules 230and one or more of the non-transitory computer readable storage devices(such as the memory 220 and/or the storage 290) form a computer programproduct that can be manufactured and/or distributed in accordance withthe present disclosure, as is known to those of ordinary skill in theart.

It should be understood that in some illustrative embodiments, one ormore of the software modules 230 can be downloaded over a network to thestorage 290 from another device or system via communication interface250 for use within the system for configuring field robots 100.

In addition, it should be noted that other information and/or datarelevant to the operation of the present systems and methods can also bestored on the storage 290, for instance various control programs used inthe operation of the acoustic devices (e.g., sensors and transducers)and/or the robots during use.

A database 285 can also be stored on the storage 290. Database 285 cancontain and/or maintain various data items and elements that areutilized throughout the various operations of the system 100. Theinformation stored in database 185 can include, but is not limited to,software and information for coordinating the operation of the acousticdevices, software and information for coordinating the movement ofrobots while deploying acoustic devices into their respective positionsduring container calibration, known characteristics used to perform theacoustic measurements and calculate container dimensions (e.g.,container wall thickness, container wall material composition, containercontents, container height, rough dimensions of the container). Itshould be noted that although database 285 is depicted as beingconfigured locally to the storage of the control computer 110, incertain implementations, database 285 and/or various of the dataelements stored therein can be located remotely and connected to thecontrol computer 110 through a network in a manner known to those ofordinary skill in the art.

A communication interface 250 is also operatively connected to theprocessor 210 and can be any interface that enables communicationbetween the control computer 110 and external devices, machines and/orelements such as the transducer, sensors and any robots used inconnection with the calibration operations. Preferably, thecommunication interface 250 includes, but is not limited to, a modem, aNetwork Interface Card (NIC), an integrated network interface, a radiofrequency transmitter/receiver (e.g., Bluetooth, cellular, NFC), asatellite communication transmitter/receiver, an infrared port, a USBconnection, and/or any other such interfaces for connecting the controlcomputer 110 to other computing devices and/or communication networks,such as private networks and the Internet. Such connections can includea wired connection or a wireless connection (e.g., using the IEEE 802.11standard) though it should be understood that communication interface250 can be practically any interface that enables communication to/fromthe control computer.

Exemplary Methods of Operation:

The operation of the exemplary container volume calibration system 100illustrated in FIG. 1 will be further appreciated with reference to FIG.3. FIG. 3 is a high-level flow diagram of a routine 300 for calibratingthe volume of a storage container according to one or more embodimentsof the invention.

The routine 300 begins at step 305, when one or more acoustic devicesare physically deployed on the container at respective positions. Morespecifically, one or more acoustic sensors and one or more acoustictransducers, such as, sensor 120A and transducer 130A, can be deployedinto respective positions on the exterior surface 155 of thecircumferential wall of the container 150 by hand or using a robot(e.g., 160) such that they are acoustically coupled to the surface andconfigured to transmit and/or receive acoustic signals that travelacross the interior volume 165 of the container.

The respective “position” of an acoustic device should be understood asreferring to the location (e.g., a point or area) on the surface of thecontainer where the device transmits and/or receives the acousticsignals. Accordingly, in an implementation for calibrating the volume ofthe cylindrical storage container 150, the position of an acousticdevice can include a particular latitude, as measured along thelongitudinal axis 116, and a circumferential position measured in thecircumferential direction 118. For instance, as shown in FIG. 1,transducer 130A has a height, h, relative to the container base 157, andis circumferentially positioned at a +270 degree angle about thecontainer's circumference (measured relative to the 0 degree referenceaxis 102). It should be appreciated that alternative three-dimensionalcoordinate and positioning systems can be utilized without departingfrom the scope of the disclosed embodiments.

At step 310, one or more acoustic signals are generated using one ormore of the deployed transducers. For instance, in the system 100 shownin FIG. 1A, the control computer 110, which is configured by executingone or more of the software modules including, for example and withoutlimitation, the acoustic control module 270, can cause the transceiver130A to generate an ultrasonic signal. The control computer can alsorecord various parameters relating to the transmitted signals including,for example, an impulse time. Other recorded parameters can include thecharacteristics of the signal such as an intensity, frequency and thelike. Preferably, the acoustic signal travels from the point of originalong a path extending across the interior volume 165 of the container150, thereby traveling through the contained medium that is in the pathof the acoustic signal.

At step 315, the one or more acoustic signals are detected using the oneor more sensors. For instance, the acoustic signals emitted bytransmitter 130A can be detected using the acoustic sensor 120A. Inaddition, at step 315, information relating to the detected acousticsignal(s) can be measured using the acoustic sensor and recorded by thecontrol computer 110 for further processing. Preferably, thisinformation includes a particular time that the arrival of the acousticsignal at the sensor is detected. In addition, the information measuredand recorded for further analysis can include characteristics of theacoustic signal such as its intensity, frequency and the like. In someimplementations, the characteristics of the one or more detectedacoustic signals can be analyzed using the control computer todistinguish between different acoustic signals and, in someimplementations, to determine various operational conditions of thecontainer (e.g., the type of medium within the container at a givenheight, the container's structural condition, and the like), as furtherdescribed herein.

Then at step 320, the control computer 110 calculates a time of flight(TOFs) for the one or more acoustic signals based on the impulse timeand respective detection times for the one or more signals. Eachrespective TOF represents the elapsed time for a signal to travelbetween two of the acoustic devices and is a function of the distancetraveled by the acoustic signal. More specifically, the control computer110, which is configured by executing one or more of the softwaremodules 130 including, for example and without limitation, the acousticanalysis module 272, can calculate a TOF for the one or more acousticsignals traveling along respective paths based on the elapsed timebetween the impulse time and respective times that the one or moresignals were detected by the transceiver. For instance, the TOF of asignal transmitted by transducer 130A and received by sensor 120A is thetime to travel along path, p, from the transducer's position to thesensor's position.

At step 325 the control computer 110 calculates the respective distancetraveled by the one or more acoustic signals based on the measured TOFsand a speed of sound through the medium within the interior volume ofthe container. More specifically, the control computer 110, which isconfigured by executing one or more of the software modules 130including, for example and without limitation, the geometric analysismodule 274, can be configured to calculate the distance traveled by anacoustic signal along its respective paths as a function of thecalculated TOF and the speed of sound through the medium. For instance,in an exemplary implementation where the transducer 130A and the sensor120A are on opposite sides of the container 150, as shown in FIG. 1, andoperating in a pitch-catch mode, with knowledge of the speed of sound inthe medium, v_(med), and the TOF measured for the acoustic signaltravelling between the transducer and the sensor, the distance, d, canthus be calculated according to the equation (d=1/1v_(med)·TOF).

At step 330, the control computer determines the dimensions of thestorage container as a function of the one or more distances calculatedat step 325 and a given alignment of the acoustic devices. Morespecifically, the control computer 110, which is configured by executingone or more of the software modules 130 including, for example andwithout limitation, the geometric analysis module 274, can be configuredto calculate the diameter of the container 150 based on the acousticallymeasured distance traveled by the one or more acoustic signals and theknown relative position of the acoustic devices that are used to measurethe one or more distances. Similarly, given the measured diameter of thecontainer, as measured from one or more positions on the container wall,the configured control computer 110 can also calculate the volume of thecontainer based on known parameters of the container including itsheight.

In implementations where a transmitting transducer and a receivingsensor are independently positioned on the surface 155 of the container150 and used to measure distance therebetween, the two devices arepreferably aligned such that the acoustic signals transmittedtherebetween travel along a path across the interior volume 165 thatpasses through the longitudinal central axis 116. In other words, thetwo devices are preferably located at diametrically opposedcircumferential positions on the wall such that the signal travelsacross a diameter of the container. In addition, it can also bepreferable for the two acoustic devices to be aligned in thelongitudinal direction 116 (i.e., at the same latitude or heightrelative to the level base 157) such that the path traveled by theacoustic signals across the interior volume is also perpendicular to thelongitudinal axis 116. Thus, where two acoustic devices are deployed atthe same latitude and on opposite sides of the container wall, thedistance, d, calculated at step 320 represents the diameter of thecontainer at the given latitude.

Although the foregoing steps for calculating the diameter of thecontainer are based on the assumption that independently deployedtransducers and sensors are aligned in both the longitudinal andcircumferential directions, TOF-based distance measurements betweenacoustic devices that are not so aligned can be similarly used tocalculate the dimensions of the container, provided that the relativeposition of the two devices is known. For instance, as illustrated inFIG. 1, where acoustic transducer 130B and the acoustic sensor 120A arelocated at different latitudes, a projected diameter of the container150 can still be calculated from an acoustically measured distancebetween the two devices, provided that the devices are circumferentiallyaligned on the outer surface 155 of the circumferential wall and theseparation between the two devices in the longitudinal direction 116(e.g., the difference between the heights of sensor 120A and transducer130B, namely, h and h1, respectively) is known.

Because the positioning and alignment of the acoustic devices used tomeasure distance is important to achieving accurate measurements of thecontainer, routine 300 can also include step 322 of aligning two or moreacoustic devices. In accordance with one or more of the disclosedembodiments, the ultrasonic container volume calibration system 100 canbe configured to automatically align two or more acoustic devices in oneor more directions relative to the surface 155 of the circumferentialwall of the container 150, for instance, the circumferential direction118 and longitudinal direction 116. The alignment can be achieved andverified using acoustic-based distance measurements and, morespecifically, based on the calculated TOFs of acoustic signals travelingbetween the devices being aligned.

In general, verifying that the devices are in alignment can includeiteratively adjusting the position of one or more of the acousticdevices on the surface of the container in one or more directions and,for each position, repeating the steps of generating, detecting andre-calculating the TOF of acoustic signal(s) until the re-calculatedTOFs indicate that the respective positions of the at least two of theacoustic devices are aligned. In some implementations, alignment canalso include adjusting the angle of a transducer relative to thecontainer, for instance, such that the acoustic signal travels acrossthe interior volume along a path that is perpendicular to thelongitudinal axis 116.

More specifically, by way of example and without limitation, the controlcomputer 110, which is configured by executing one or more of thesoftware modules 230, including, for example and without limitation, theposition control module 276, can position and re-position the transducer130C measured amounts in the longitudinal direction 116 along thesurface 155 using the robot 160. Moving the transducer measured amountsin one or more directions on the container wall can be controlled basedon position measurements gathered in near-real time, for instance, usingone or more sensors that are on-board the robot that are suitable formeasuring absolute position or relative position and movement of therobot (e.g., a GPS sensor, accelerometers, altitude sensors, and thelike). For each new position of the robot and hence the transducer, thecontrol computer can perform the steps of: generating one or moreacoustic signals using the transducer, detecting the acoustic signals bythe particular sensor that the transducer is being aligned with andcalculating TOFs for the one or more signals. As noted, the controlcomputer can be configured to cause the robot to separate the transduceror other acoustic device from the container, reposition the robot, thenplace the acoustic device back into engagement with the container at thenew location. Preferably, when attempting to align the transducer 130Cwith a particular sensor, say, sensor 120B, TOF is calculated for theacoustic signals detected by the particular sensor 120B.

Because the TOF of soundwaves traveling between a transducer and aparticular sensor are directly proportional to distance therebetween,alignment of the two devices in the longitudinal direction 116 can beachieved by iteratively moving the transducer (and/or the sensor) alongthe surface 155 in the longitudinal direction until a minimum value ofTOF for a pulse traveling therebetween is identified. Similarly,alignment in the circumferential direction 118 can be achieved based oniteratively moving the transducer along the surface 155 (and/or thesensor) in the circumferential direction and re-measuring TOF until theTOF indicates that the devices are circumferentially aligned. Forinstance, assuming that the relative longitudinal position of transducer130C and sensor 120B does not change, the two devices can be determinedby the control computer to be circumferentially aligned (i.e., locatedat directly opposite circumferential positions) on the surface 155 ofthe wall when the TOF of acoustic signals traveling therebetween is at amaximum.

As previously noted, in some implementations, the calibration system 100can be configured to measure the dimensions of the container 150 atdifferent positions on the surface 155 in the longitudinal direction 116and, in addition or alternatively, in the circumferential direction 118.Using distance measurements obtained in multiple dimensions, the controlcomputer 110 can thus be configured to generate a model of the interiorvolume of the container with a greater degree of resolution andaccuracy. Accordingly, the control computer 110 can be configured torepeat one or more of the steps of routine 300 (e.g., steps 305-325) forany number of different combinations of previously deployed sensors andtransducers.

In addition or alternatively, at step 340, one or more of the acousticdevices can be re-positioned prior to re-measuring the distance betweenacoustic devices in view of the new position(s). For instance, the robot160 can be configured to move acoustic transducer 130C from a firstlatitude to a second latitude such that the diameter of the containercan be re-measured at the second latitude, and can thereafter move thetransducer to another position, as necessary.

One or more steps of the exemplary routine 300 for measuring TOF anddistance between acoustic devices using acoustic/ultrasonic measurementcan be similarly implemented using various different transducer andsensor configurations and modes of operation. The remaining figures andcorresponding discussion further illustrate various configurations andconcepts of the ultrasonic container volume calibration system inaccordance with one or more of the disclosed embodiments of theinvention.

FIGS. 4A-9 illustrate exemplary container volume calibration systemshaving a variety of different acoustic device arrangements and modes ofoperation in accordance with one or more of the disclosed embodiments.It should be appreciated that the various acoustic devices illustratedin FIGS. 4A-4D are configured to be in communication with a controlcomputer 110 (communication connection not shown) that coordinatesoperation of the acoustic container volume calibration system.

FIG. 4A is a high-level diagram showing a side-view and a top-plan viewof an exemplary ultrasonic container volume calibration system 400Adeployed on a container 450. The system 400A includes an ultrasonictransducer and sensor that are integrated into a singular transceiverunit 430A disposed on the exterior surface 455 of the circumferentialwall of the container. In this exemplary configuration the transceivercan be configured to both transmit (Tx) and receive (Rx) acousticsignals (i.e., can operate in pulse-echo mode). As shown, thetransceiver 430A is positioned at a height h on the wall, as measured inthe longitudinal direction 416, and can be operated using the controlcomputer 110 to measure the diameter of the container at height h.

More specifically, the transceiver 430A can be configured to transmit anacoustic signal along a path across the interior volume of thecontainer. The signal can be reflected by the interior surface of thecircumferential wall on the opposite side of the container, such that atleast a component of the reflected signal travels back along the path,p, toward the point of origin. Accordingly, the sensor component of thetransceiver 430A, which is provided at effectively the same position asthe transducer component, can be configured to detect the reflectedacoustic signal and record the detection time and can also measure othercharacteristics of the received signal. FIG. 4B is a conceptualside-view diagram illustrating the travel of such an acoustic signalduring operation of system 400A. As shown, the acoustic signal travelsalong the path, p, between the transceiver 430A and the interior surface457 of the opposing side-wall. FIG. 4B also conceptually illustrates theTOF, which is the total “return time” for the acoustic signal to travelfrom the transceiver to the opposing wall and for a reflected componentof the signal to travel back to the transceiver. FIG. 4B alsoillustrates the relationship between the distance between the transducerand the opposing wall, d, which is half the total distance traveled bythe acoustic signal, 2d. Accordingly, with knowledge of the speed ofsound in the medium, v_(med), the distance between the transceiver andthe opposing wall, d, can thus be calculated according to the equation(d=½v_(med)·TOF).

In addition, the transceiver 430A can also be configured to be moved onthe surface in one or more directions. For instance, as shown in FIG.4C, the transceiver 430A can be mounted to a moveable robotic platform460A, which is configured to autonomously or semi-autonomously move thetransceiver into any number of different latitudes on the surface 455 ofthe container 450. Accordingly, the control computer 110 cancontrollably measure the diameter of the container at each respectivelatitude. In addition or alternatively, the transceiver 430A can bemoved in other directions on the surface, namely, circumferentially,such that the container's diameter can be measured at multiple positionsabout the container's circumference, for instance, to determine theuniformity of the container's diameter at a given latitude.

Preferably, the acoustic transducer 430A operating in pulse echo mode isacoustically coupled to the surface 455 such that the acoustic signaltravels to the inner surface of the opposing side of the container andis reflected back along the same path (e.g., a path that passes throughthe central longitudinal axis 416 of the cylindrical container andperpendicular thereto). Accordingly, positioning the transceiver caninclude the step of automatically aligning the transceiver relative tothe surface 455 of the container so as to control the directionality ofthe acoustic signal transmitted. For instance, in some implementations,the robotic platform under the control of the control computer 110, canbe configured to systematically adjust the angle of the transceiver 430Arelative to the surface 455 until the acoustic signals is determined totravel along a path that passes perpendicularly through the longitudinalaxis 416 (e.g., along a given latitude and normal to the opposing sideof the container). The control computer can be configured to verifyproper alignment based on one or more measured characteristics of thereceived acoustic signals (e.g., TOF, intensity, frequency and thelike).

In accordance with one or more of the disclosed embodiments, FIG. 5illustrates another exemplary ultrasonic container volume calibrationsystem 500 deployed on a container 550. The system 500 that includes anarray 530 of transceiver units disposed on the exterior surface of awall 555 of the cylindrical container. Like the transceivers describedin connection with FIG. 4A, the individual transceivers 1-n eachcomprise a transducer and sensor component and are configured to operatein both transmit (Tx) and receive (Rx) modes. As shown in FIG. 5, thetransceivers can be provided at respective latitudes on the surface ofthe wall 455. In some implementations, the transceivers can be fixed atthe respective positions. In addition or alternatively, one or more ofthe transceivers can be moveable in one or more directions on thesurface.

It can be appreciated that, in accordance with the exemplary methodsdescribed in connection with FIGS. 1, 3 and 4A-4C, using the transducers530A-N, individually, the control computer 110 can measure the diameterof the container 550 at the respective latitude of each transducer. Aspreviously noted, in the case of systems using more than one transduceror transceiver, it can be preferable to use a phased array, wherein theacoustic pulses sent out by each element of the array is controlled intime, thus allowing for the differentiation between signals. Inaddition, or alternatively, another method that can be employed todifferentiate the signals of respective transducers is for thetransducers to operate at different respective frequencies for emissionand reception. Although exemplary embodiments described herein measuredistance between two devices operating as a pair, say, a first and asecond transceiver, signals emitted by one device can be received by anynumber of other devices, i.e. a third transceiver, in a similar fashionto the “pitch and catch” between the first and second transceivers. Inthis way, the time of flight between the first and third transceiverswill allow for calculation of the path distance there-between and thuscalculation of the volume, provided that the relative positions of thedevices is known (e.g., measured during device placement).

In accordance with one or more of the disclosed embodiments, FIG. 6illustrates another exemplary ultrasonic container volume calibrationsystem 600 deployed on a container 650. System 600 includes multipleacoustic devices including a transducer 630 and a sensor 620 disposed atrespective positions on the exterior surface 655 of the circumferentialwall of the cylindrical container. In such a configuration thetransducer is configured to operate in transmit (Tx) mode, whereas thesensor is configured to operate in receive (Rx) mode. Accordingly, asdescribed in connection with FIG. 3, the transducer and sensor pair canbe configured to operate together in pitch-catch mode, namely,transmitting acoustic signals directly between the transducer and thesensor such that TOF along the direct flight-path can be measured anddistance therebetween can be calculated. In addition, the transceiver430C and sensor 420 can also be configured to be moved in thelongitudinal direction 616, for instance, to enable the measurement ofthe container's diameter at different latitudes. In addition oralternatively, the transducer and sensor can also be moved in otherdirections on the surface, namely, the circumferential direction, so asto measure diameter at multiple positions about the circumference of thecontainer.

In accordance with one or more of the disclosed embodiments, FIG. 7illustrates another exemplary ultrasonic container volume calibrationsystem 700 deployed on a cylindrical container 750. System 700 includesan array 730 of transducer devices 730-1 to 730-n and an array 720 ofsensor devices 720-1 to 720-n disposed on the exterior surface 755 of acircumferential wall of the container. In such a configuration eachtransducer can be configured to operate in transmit (Tx) mode, whereaseach sensor can be configured to operate in receive (Rx) mode such thatone or more of the transducers in array 730 and one or more of thesensors in array 720 can be configured to operate together inpitch-catch mode. As shown, the transducers and sensors can be providedat opposing circumferential positions. The devices can also be providedat respective latitudes and the respective positions can be fixed.Preferably, each one of the transducers is positioned at the samelatitude as one of the sensors thereby defining respective pairs, forinstance, transducer 730-1 and corresponding sensor 730-1 define a pairat a given height. However, in some implementations, individualtransducers and sensors are not necessarily paired-up in a one-to-onefashion or at the same latitude as another device. In addition oralternatively, in some implementations, one or more of the acousticdevices can be moveable in one or more directions along the surface ofthe wall.

FIG. 8 is a top view of an exemplary ultrasonic container volumecalibration system 800 deployed on a container 850, in accordance withone or more of the disclosed embodiments. As shown, system 800 includesan array 830 of acoustic devices 830A-830L disposed circumferentiallyabout the exterior surface 855 of a circumferential wall of thecylindrical container. As shown, the devices are spaced about thecomplete circumference of the container. In the exemplary system 800,devices that are at opposing circumferential positions on thecylindrical container, e.g., transducer/transceiver 830A andsensor/transceiver 830G, can operate in transmit and receive modes,respectively. By way of further example, FIG. 9 is a top view of anexemplary ultrasonic container volume calibration system 900 deployed ona circumferential side-wall 955 of a container 950. As shown in FIG. 9,the system 900 includes acoustic devices spaced 930A-930G about a partof the circumference of the container, for instance, half of thecircumference of the container. As the acoustic devices are only spacedabout part of the circumference, preferably, transceivers operating inboth transmit and receive modes are used.

In the exemplary implementation shown in FIG. 8, the location of thetransducers about the circumference of the container can be operatedusing the control computer 110 to provide a cross-sectional image of thetank and its contents. For instance, known mathematical algorithms canbe used to generate the image such as back projection algorithm (i.e.radon transfer) and other such algorithms. In implementations such asillustrated in FIG. 9 where the acoustic devices provide partialcoverage of the container's circumference, the control computer canstill be configured to generate a cross sectional image of the containerusing similar mathematical techniques. It should also be noted that thenumber of transducers used is directly proportional to the resolution ofthe image of the container volume that can be generated using thecontrol computer.

It should be understood that a combination of the configurations andmodes of operation described in connection with FIGS. 5A-9 can beutilized to acoustically calibrate the volume of containers inaccordance with one or more of the disclosed embodiments. For example,the container volume measurements taken utilizing fixed arrays ofacoustic devices can be supplemented by measurements taken usingrobot-mounted acoustic devices configured to measure containerdimensions at locations that are not otherwise monitored by the fixeddevices and otherwise hard to reach locations on the wall of thecontainer. By way of further example, although FIGS. 8 and 9 depict onlya single acoustic device placed at respective circumferential positions,in some implementations, a longitudinally oriented array of devices canbe deployed at one or more of the respective circumferential positionson the container wall, for instance, as described in connection withFIGS. 5 and 7. In implementations where arrays comprise transducers (ortransceivers) arranged in the longitudinal direction (e.g., spaced aparton the surface of the wall in a vertical line relative to the base) andwhere several such arrays are placed around the circumference of thetank, the use of multiple arrays can allow measurement of the tank atdifferent points in the longitudinal and circumferential direction. Theresolution of the container volume models or images generated by thecontrol computer 110 can depend on the number of devices in each arrayas well as the number of arrays deployed onto the wall of the container.Accordingly, with a sufficient number of longitudinal arrays locatedaround the circumference of the tank the control computer can generate asufficiently detailed two-dimensional or three-dimensional images of thecontainer volume and its contents.

As noted, in addition to measuring the volume of a container, theexemplary systems and methods for acoustically calibrating the volume ofstorage containers can also be configured to acoustically determineoperational characteristics of the container including, the type ofcontents within the container, the volume of such contents and evaluatethe structural integrity of the container walls.

More specifically, the acoustic measurements can be used to measure thelevel of liquid(s) within the tank thereby allowing a calculation of theliquid volume. For instance, when utilizing an array of acoustic devicesspaced apart to measure the diameter of the tank at respectivelatitudes, the control computer can be configured to analyze thecharacteristics of the signals measured at respective latitudes toidentify a level of an interface between two different mediums, say, aninterface between petroleum and air. Accordingly, the volume ofpetroleum within the container can be determined based on the interfacelevel and the volume of the portion of the container that extendsbetween the base and the interface level, or, by way of further example,the height difference between the oil/air interface and an oil/waterinterface closer to the base).

By way of further example, as a result of the different speeds of soundin media (e.g., in this particular application hydrocarbon, air andwater) the calibrated system can differentiate between each media. Forinstance, in the case of air, there typically will be no signal due tohigh signal attenuation at the operating frequency of the transducers.Accordingly, the system can determine the interface between oil and airat the point where no signal is received.

In addition, with knowledge of the speed of sound of the acousticsignals in the medium, the system can be further configured to classifythe specific type of product contained within the storage container.More specifically, as would be understood by those in the art, the speedof sound in air (330 m/s) is quite different from the speed of sound inthe media contained with the storage vessel. The speed of sound in wateris close to 1484 m/s, and the speed of sound through kerosene is closeto 1324 m/s. As a practical example, transmitting an acoustic signalover a distance of 30 meters would equate to a time of flight (returnjourney) of 40.43 seconds for water and 45.31 seconds for kerosene.Accordingly, with calibration of the container dimensions or expectedtimes of flight, the system can be configured to determine the liquid inthe tank at a given level measured with a transducer according to thedifference in time of flight.

Moreover, the foregoing concepts can also be used to identify thepresence of other liquids, e.g., water at the bottom of the petroleumstorage container. Such information can be used to ensure an accuratedetermination of the volume of container contents and thus ensure thecorrect transfer of product to and from the container and potentiallyavoid contamination of other tanks/vessels.

As noted, the system can also be configured to evaluate the structuralintegrity of the container walls, preferably. The system can beconfigured to measure container integrity independent of or inconnection with the processes for measuring container volume. Morespecifically, the system can be configured to transmit an acousticsignal using a transceiver (operating in Tx and Rx mode) and, when theacoustic signal is initially sent by a transceiver, part of the signalwill be reflected off the boundaries of the container wall, while partof it will transmit through the internal volume as described above. Thesignal that reflects off the boundary (i.e., internal surface of thecontainer wall) will represent information on the thickness of thevessel and can be received and measured using the transducer. Inparticular, based on a known speed of sound in the wall material and thetime of flight (return trip to boundary wall) the system can calculatethe thickness of the wall. In addition or alternatively, a highfrequency transducer can be used to measure the integrity of theinternal structure of the boundary walls of the container, e.g.,cracking and blistering, based on the measured return time of flight andspeed of sound in the material. Accordingly, in another exemplaryconfiguration, the system can incorporate a dual frequency transducer,wherein signals emitted at a high frequency can be analyzed to measurevessel integrity and lower frequency signals can be analyzed to performthe time of flight measurement of container dimensions. In addition, insuch dual-frequency transceiver configurations, electronic filteringtechniques can also be applied to remove noise, as necessary (e.g.,using a Low and/or High Pass filter).

At this juncture, it should be noted that although much of the foregoingdescription has been directed to systems and methods for ultrasoniccalibration of the volume of storage containers, the systems and methodsdisclosed herein can be similarly deployed and/or implemented inscenarios, situations, and settings far beyond the referenced scenarios.For instance, the exemplary systems and methods can be adapted toacoustically measure the volume of containers without limitation toultrasonic acoustic devices.

Although the exemplary systems and methods for measuring containervolume based on acoustics are described above in the context of aparticular practical application, namely, measuring the volume of largepetroleum storage containers having a cylindrical shape and metallicconstruction, it should be understood that the disclosed embodiments ofthe invention are not limited to this exemplary application. Forinstance, the disclosed systems and methods can be used to measure thevolume of storage containers having alternative shapes (e.g., sphericalcontainers, cube-shaped containers and the like). For example andwithout limitation, in the case of a cube shaped container, the methodsdisclosed above can be similarly applied to align acoustic devices onthe exterior surface of the container along a longitudinal axis and/ortransverse axis, acoustically measure the distance between opposingwalls of the container at multiple heights and multiple positions aboutthe periphery of the container and, accordingly, generate two or threedimensional maps of the interior volume of the container, its contentsand the like.

It should be appreciated that more or fewer operations can be performedthan shown in the figures and described. These operations can also beperformed in a different order than those described. It is to beunderstood that like numerals in the drawings represent like elementsthrough the several figures, and that not all components and/or stepsdescribed and illustrated with reference to the figures are required forall embodiments or arrangements.

Thus, illustrative embodiments and arrangements of the present systemsand methods provide a system and a computer implemented method, computersystem, and computer program product for ultrasonic calibration of thevolume of storage containers. The flowchart and block diagrams in thefigures illustrate the architecture, functionality, and operation ofpossible implementations of systems, methods and computer programproducts according to various embodiments and arrangements. In thisregard, each block in the flowchart or block diagrams can represent amodule, segment, or portion of code, which comprises one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that, in some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising”, when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having,” “containing,” “involving,” andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

The subject matter described above is provided by way of illustrationonly and should not be construed as limiting. Various modifications andchanges can be made to the subject matter described herein withoutfollowing the example embodiments and applications illustrated anddescribed, and without departing from the true spirit and scope of thepresent disclosure, which is set forth in the following claims.

What is claimed is:
 1. A method of measuring an interior volume of astorage container containing a medium therein using a plurality ofacoustic devices, the method comprising: deploying the plurality ofacoustic devices into respective positions on an exterior surface of acircumferential wall of the container, the acoustic devices including anultrasonic transducer and an ultrasonic sensor, wherein the transduceris acoustically coupled to the surface and is configured to transmit oneor more ultrasonic signals through the wall of the container and acrossthe interior volume of the container, and wherein the sensor isacoustically coupled to the surface and configured to detect the one ormore ultrasonic signals; transmitting one or more ultrasonic signalsusing the transducer, wherein each signal is transmitted at a respectiveimpulse time; detecting, using the sensor, the one or more signals andrecording a respective detection time; calculating, by a computingdevice in electronic communication with the transducer and the sensor,respective times of flight (TOFs) for the one or more signals based onthe respective impulse times and respective detection times, wherein arespective TOF is an elapsed time for a signal to travel along a pathbetween the respective positions of the transducer and the sensor;aligning, with the computing device based on the respective TOFs, theone or more of the transducer and the sensor in one or more of acircumferential direction and a longitudinal direction relative to thecircumferential wall of the container; calculating, with the computingdevice, a distance between the respective positions of the alignedtransducer and sensor based on the calculated respective TOF and a speedof sound through the medium; and determining, with the computing device,the volume of the storage container based on the calculated distance andthe respective positions of the aligned transducer and sensor.
 2. Themethod of claim 1, wherein the step of aligning comprises: adjusting therespective position of one or more of the transducer and the sensor onthe surface in one or more of the circumferential direction and thelongitudinal direction, and performing the steps of transmitting,detecting and calculating respective TOFs for one or more acousticsignals transmitted between the adjusted respective positions of thetransducer and sensor.
 3. The method of claim 2, repeating theadjusting, transmitting, detecting and calculating steps untildetermining, with the computing device based on the calculated TOFs,that the transducer and the sensor are aligned.
 4. The method of claim3, wherein the step of adjusting the respective position of one or moreof the transducer and the sensor on the surface comprises: moving one ormore of the transducer and the sensor a prescribed amount in one or moreof the longitudinal and the circumferential direction using a robotoperating under the control of the computing device, wherein theprescribed amount is measured in near-real time using one or moreposition sensors on-board the robot and wherein the robot is configuredto move according to a feedback control loop.
 5. The method of claim 1,further comprising: deploying a plurality of sensors at differentrespective positions on the surface; iteratively aligning, using a robotunder the control of the computing device, the transducer with each oneof the plurality of sensors; performing the steps of generating,detecting and calculating respective TOFs for each respective positionof the transducer that is aligned with one of the plurality of sensors;and calculating, based on the calculated TOFs, a diameter of thecontainer for each respective position of the transducer that is alignedwith one of the plurality of sensors.
 6. The method of claim 1, furthercomprising: adjusting the respective position of one or more of thetransducer and the sensor on the surface in one or more of thecircumferential direction and the longitudinal direction using one ormore robots under the control of the computing device, and performingthe steps of transmitting, detecting and calculating respective TOFs forone or more acoustic signals transmitted between the adjusted respectivepositions of the transducer and sensor.
 7. The method of claim 1,further comprising: prior to the step of calculating the distance,measuring the speed of sound in the medium.
 8. The method of claim 7,wherein the step of measuring the speed of sound in the mediumcomprises: deploying a particular transducer and a particular sensor atrespective positions on the surface having a known distancetherebetween; measuring, with the computing device using the particulartransducer and sensor, TOF for at least one acoustic signal transmittedbetween the particular transducer and the particular sensor; andcalculating, with the computing device, the speed of sound through themedium based on the TOF of the signal traveling between the transducerand the particular sensor and the known distance.
 9. The method of claim1, further comprising: identifying, with the computing device based onthe calculated respective TOFs, one or more of: a type of a mediumcontained within the storage container, a volume of the medium containedwithin the storage container.
 10. The method of claim 1, wherein thetransducer and the sensor are combined into an acoustic transceiver unitthat is configured to both transmit and receive the one or moreultrasonic signals, and wherein the step of aligning comprises:controllably positioning the transceiver relative to the circumferentialwall of the container such that the one or more acoustic signals travelalong a path extending across the internal volume of the container alonga diameter of the container.
 11. A system for measuring a volume of astorage container, the system comprising: a plurality of acousticdevices configured to be acoustically coupled to an exterior surface ofa circumferential wall of the container at respective positions, theacoustic devices including: an ultrasonic transducer configured totransmit one or more ultrasonic signals across an interior volume of thecontainer that is bounded by the wall, and an ultrasonic sensorconfigured to detect the one or more ultrasonic signals; a robotconfigured to controllably deploy one or more of the acoustic devices onthe surface, wherein the robot includes a drive system and one or moreposition sensors for monitoring a position of the robot; and a controlcomputing system comprising: a non-transitory computer readable storagemedium, one or more processors in electronic communication with theplurality of acoustic devices, the robot and the computer readablestorage medium, one or more software modules comprising executableinstructions stored in the storage medium, wherein the one or moresoftware modules are executable by the processor and include: anacoustic control module that configures the processor to, using thetransducer, transmit one or more acoustic signals at respective impulsetimes, wherein the acoustic control module further configures theprocessor to, using the sensor, detect the arrival of the one or moresignals and record respective detection times, an acoustic analysismodule that configures the processor to calculate a respective time offlight (TOF) for the one or more acoustic signals traveling between therespective positions of the transducer and the sensor, and calculate arespective distance therebetween based on the respective TOF, a positioncontrol module that configures the processor to, using the robot, adjustthe respective position of one or more of the transducer and the sensoron the surface and, for each adjusted respective position, re-calculatea respective distance between the transducer and the sensor based on oneor more acoustic signals traveling therebetween, and a geometricanalysis module that configures the processor to calculate a volume ofthe storage container based on the calculated respective distances andcorresponding respective positions of the transducer and the sensor. 12.The system of claim 11, wherein the position control module configuresthe processor to iteratively adjust the respective position of one ormore of the transducer and the sensor on the surface and re-calculatethe respective distance until determining that the transducer and sensorare aligned.
 13. The system of claim 11, further comprising: a pluralityof ultrasonic sensors including at least a first acoustic sensor and asecond acoustic sensor, wherein the plurality of sensors are separatedby a known distance in one or more of a circumferential direction and alongitudinal direction.
 14. The system of claim 13, wherein the positioncontrol module configures the processor to, using the robot, align thetransducer with each of the plurality of sensors in the longitudinaldirection and circumferential direction and, for each respectiveposition in which the transducer is aligned with one of the plurality ofsensors, calculate a respective diameter of the container based on thecalculated TOFs.